Method of making blind sealing rivets



Oct. 20, 1970 R. R. DEANS E AL METHOD OF MAKING BLIND SEALING RIVETS Filed Feb. 9, 1968 Hail,

m 558 n VI ma w TeP M #0 M T M A 8h \0 mmv B United States Patent METHOD OF MAKING BLIND SEALING RIVETS Robert R. Deans, Marshfield, Mass., and Anthony M.

Putetti, Waterbury, Conn., assignors to Scovill Manufacturing Company, Waterbury, Conn., a corporation of Connecticut Filed Feb. 9, 1968, Ser. No. 704,477 Int. Cl. B21k 1/44; B23g 9/00 US. C]. 10-27 2 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a method of making blind sealing rivets.

As distinguished from an earlier method of making such rivets disclosed in Curtis Re. Pat. No. 24,363 with several machines and intermediate annealing steps, the present method requires only one automatic machine wherein the complete rivet may be formed without intermediate annealing.

Instead of extruding the material from a short thick walled blank around the head of the pulling stem, the metal is formed before introducing the stem, into a long tubular shape where the inner portion around the closed end wall is of reduced diameter substantially the same as the finished rivet, so that it is only necessary to force the shell wall inwardly against the stem with only minimal further elongation and without any extrusion around the head of the pulling stem. The term long as applied to the tubular shape is intended to define a length of the order of two to four times the outside diameter.

In the accompanying drawings, I have shown for purposes of illustration, one embodiment which the invention may assume in practice. In these drawings:

FIG. 1 is an elevation of the original blank as may be cut from a rod;

FIG. 2 shows the blank partially in section after a preforming step;

FIG. 3 is a central vertical section of the long tubular shape as drawn or extruded from the blank of FIG. 2, with the pulling stem in position to be inserted;

FIG. 4 is a sectional view showing the pulling stem in place and the beginning of the closing operation which forces the sidewall of the tubular shape against the stem;

FIG. 5 shows the completion of the closing operation in section;

FIG. 6 is a sectional view showing the head forming step;

FIGS. 7 and 8 are sectional views showing the manner of using such a closed end rivet before and after the upsetting operation.

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The blank 10 may first be formed into the shape shown in FIG. 2 where it has rounded corners 11 and a recess 12 in one end face. By means of a suitable punch and die, this blank is drawn or extruded into the generally tubular shape shown in FIG. 3, having a long cylindrical sidewall 13, a cylindrical bore 14 and a closed inner end wall 15. The inner end portion 16 of this shape is of reduced outside diameter, the axial extent of such reduced diameter portion being at least as great as the thickness of the end wall 15 and preferably also enough to extend further over head 17 of a pulling stem 18.

After the pulling stem is inserted so that head 17 abuts the end wall 15, a bending or closing tool 19 is pushed over the wall 13 to force this wall inwardly against the stem 18. A cylindrical hole 20 in the tool 19 is sized to fit around the reduced end portion 16 and the end of this tool around the opening 20 is flared as indicated at 21 so as to come into engagement with a corner 22 of the wall 13, it being noted that the beveled surface 23 between wall 13 and the reduced end 16 has a somewhat greater angle than the flare 21 0f the forming tool.

The stroke of the tool 19 is such that it will end at about the position shown in FIG. 5 leaving a bellmouthed end 24 of the same outside diameter as the original wall 13. From the bellrnouth, a rivet head 25 is formed by a suitable punch 26 and by 27. The end of punch 26 is so shaped as to form an undercut 28 on the inner surface of the rivet head.

When the forming tool 19 starts to operate, it will bend the wall 13 inwardly so as to form an internal shoulder 29 extending at least partially into a neck 30 and engage behind head 17 of the pulling stem. When the finished rivet is inserted through preformed holes in the material to be riveted, for example, metal sheets 31, a blind riveting tool which grips the protruding part of stem 18 and applies pressure to the rivet head 25, will upset that portion of the rivet wall outwardly of the pulling stem head 17, to form a bulge 32 and provide a leakproof joint between the rivet and the plates 31.

It will be evident that with my improvement no severe extrusion of the metal around the pulling stem head is required, and that the entire series of operations is such that it can be performed without intermediate annealing steps, in a single automatic machine.

I claim:

1. A method of making a blind sealing rivet without intermediate annealing steps, comprising the steps of (a) cold-forming a metal blank into a generally tubular shape having a closed inner end wall, a long cylindrical sidewall, and a long cylindrical bore of substantially uniform diameter;

(b) inserting a headed rivet-setting pulling stem into said bore until its head abuts said end wall;

(c) forcing said cylindrical wall inwardly toward said stem and to provide an internal shoulder to engage behind the head of said pulling stem with only minimal further elongation of said sidewall, and leaving a bellmouth in the outer end of the tubular shape; and

(d) by swaging, forming a rivet head from the material of said bellmouth.

2. The method defined in claim 1 wherein the gen- 2,779,955 2/ 1957 Curtis 29-517 X erally tubular shape of clause (a) has a portion at its 3,300,798 1/ 1967 York 10-27 inner end of reduced outside diameter substantially equal to the outside diameter of the cylindrical wall of the FOREIGN PATENTS finished rivet, the axial extent of such reduced diameter 13 1 4 Great Britain portion being at least as great as that of said closed end 5 wall. CHARLIE T. MOON, Primary Examiner References Cited UNITED STATES PATENTS X- 1,169,642 1/1916 Heeter et a1 29-517 X 10 29-510, 520, 522; 85-70, 72

2,040,939 5/1936 Huck 10-27 

